What if we could find alien life not by looking at what it is made of, but by what it does? That is the idea behind a new model of life that focuses on function over form, and on information over matter.
The model is based on the concept of semantic information, which refers to data that is meaningful to a system. For living systems, semantic information is the information that helps them stay alive, such as how to sense their environment and respond in complex ways.
This perspective could help us reimagine what alien life might look like, and how to search for it. Traditional assumptions about alien life forms — which usually assume they are carbon-based and require water and DNA — may be too narrow.
Taking an informational perspective could be a step in the right direction toward understanding life as a universal phenomenon.
The model was developed by a team of researchers led by Adam Frank, a professor of physics and astronomy at the University of Rochester and the author of The Little Book of Aliens.
Their paper, titled “Semantic Information in a Model of Resource Gathering Agents,” was published this week in PRX Life, a journal in the prestigious Physics Review X series.
The paper presents a simple mathematical model of agents that gather resources from their environment to survive and reproduce. The agents use semantic information to decide which resources are valuable and which are not.
The model shows how semantic information emerges naturally from the interaction between the agents and their environment, and how it evolves over time.
The researchers hope that their model can serve as a starting point for exploring the role of semantic information in living systems, and how it can be used to identify signs of life on other planets.
“We don’t need to think about what life is made of but rather what it does,” Frank said in a blog post on Big Think. “We are finally ready to look for what is out there in a systematic way.”
In our search for and (potential future study of) life that forms elsewhere in the Universe, we want to be agnostic about its underlying structure. That means we don’t want to assume it is carbon-based, needs water, or requires DNA.
Taking an informational perspective is one way to achieve that agnosticism. We don’t need to think about what life is made of but rather what it does. One thing that seems like a good bet to be universal is that life processes information.
That’s why our new results on semantic information and its thresholds may be a step in the right direction toward understanding life as a universal phenomenon.